In general, an organic light emitting phenomenon refers to a phenomenon in which electric energy is converted into light energy by means of an organic material. An organic electrical element utilizing the organic light emitting phenomenon usually has a structure including an anode, a cathode, and an organic material layer interposed therebetween. Here, in many cases, the organic material layer may have a multilayered structure including multiple layers made of different materials in order to improve the efficiency and stability of an organic electrical element, and for example, may include a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and the like.
A material used as an organic material layer in an organic electrical element may be classified into a light emitting material and a charge transport material, for example, a hole injection material, a hole transport material, an electron transport material, an electron injection material, and the like according to its function. Further, the light emitting material may be divided into a high molecular weight type and a low molecular weight type according to its molecular weight, and may also be divided into a fluorescent material derived from electronic excited singlet states and a phosphorescent material derived from electronic excited triplet states according to its light emitting mechanism. Further, the light emitting material may be divided into blue, green, and red light emitting materials, and yellow and orange light emitting materials required for better natural color reproduction according to its light emitting color.
Meanwhile, when only one material is used as a light emitting material, there occur problems of shift of a maximum luminescence wavelength to a longer wavelength due to intermolecular interactions and lowering of the efficiency of a corresponding element due to a deterioration in color purity or a reduction in luminous efficiency. On account of this, a host/dopant system may be used as the light emitting material in order to enhance the color purity and increase the luminous efficiency through energy transfer. This is based on the principle that if a small amount of dopant having a smaller energy band gap than a host forming a light emitting layer is mixed in the light emitting layer, then excitons generated in the light emitting layer are transported to the dopant, thus emitting light with high efficiency. With regard to this, since the wavelength of the host is shifted to the wavelength band of the dopant, light having a desired wavelength can be obtained according the type of the dopant.
In order to allow an organic electrical element to fully exhibit the above-mentioned excellent features, it should be prerequisite to support a material constituting an organic material layer in the element, for example, a hole injection material, a hole transport material, a light emitting material, an electron transport material, an electron injection material, or the like, by a stable and efficient material. However, such a stable and efficient organic material layer material for an organic electrical element has not yet been fully developed. Accordingly, there is a continuous need to develop new materials for an organic material layer.